The present invention relates to an airbag apparatus that inflates an airbag to protect an occupant from an impact that is applied to a vehicle such as a car due to a collision or the like.
An air bag apparatus is effective for protecting an occupant when an impact is applied to a vehicle such as a car. For example, an airbag apparatus disclosed in Japanese National Phase Laid-Open Patent Publication No. 2007-530364 has been known. The airbag apparatus includes an airbag 81 and an inflator 82 as shown in FIGS. 7(A) and 7(B).
The airbag 81 is formed by sewing a base fabric 83 to form a bag and includes a seam A and an inflation portion B, which is surrounded by the seam A. The seam A includes seam sections 84, 85, which are adjacent to each other. The seam sections 84, 85 are connected to and intersect each other at an intersecting portion 89. The seam sections 84, 85 have end parts 84A, 85A, respectively. The end parts 84A, 85A are located farther from the center of the inflation portion B than the intersecting portion 89.
The airbag 81 also has an additional seam section 88, which divides the inflation portion B into an upper inflation portion 86 and a lower inflation portion 87. The intersecting portion 89 of the seam sections 84, 85 faces the lower inflation portion 87.
According to the above described airbag apparatus, the inflator 82 supplies inflation gas to the inflation portions 86, 87 when an impact is applied to components of a vehicle, so that the airbag 81 is deployed and inflated. The deployed and inflated airbag 81 is located between an occupant and a vehicle component that bulges into the vehicle to absorb the energy of the impact, so that the occupant is protected.
When the inflation portions 86, 87 are inflated by inflation gas, parts of the seam A that face the inflation portions 86, 87 (that is, the surrounding parts) directly receive the pressure of the inflation gas. Regarding the seam sections 84, 85, parts except for the end parts 84A, 85A (that is, parts outside of the intersecting portion 89) directly receive the pressure of the inflation gas.
In the seam A, the seam section 84 is formed, for example, after the seam section 85 is formed. In this case, when the seam section 84 is formed, a sewing needle may damage the threads of the seam section 85, which has been formed previously, by being pierced into the seam section 85. If the threads of the seam section 85 are damaged in this manner, the strength of the intersecting portion 89 will be reduced. As a result, when the seam A receives the pressure of inflation gas, the seam section 85 may be broken at the intersecting portion 89. Starting from the broken part, other parts of the seam section 85 may start fraying as shown by lines formed by a long dash alternating with two short dashes in FIG. 7(C). Such breakage of the seam section 85 can be a cause of leakage of inflation gas from the inflation portion 87 to the outside.